Wrapping bales of fresh or wilting grass with a ductile and adhesive film is currently growing more and more popular because the tightly wrapped bales—apart from other advantages—mature into silage within the film wrap in a relative short period of time without releasing silage fluid that damages the environment, as is the case with clamp silos or silage towers.
Both round and rectangular bales can be wrapped. Currently basically two bale wrapping systems have been introduced into practice. In the case of the so-called wrapping table system, subsequent covering layers of film are placed two to three times around the entire outer bale circumference during the rotation of the bale around a horizontal axis and simultaneous rotation around a vertical axis. In the case of the so-called rotary arm system, the bale is also placed on a type of wrapping table that rotates the bale around its horizontal longitudinal axis, however the wrapping table does not simultaneously rotate around its vertical axis but instead the relative rotation between the bale and the dispensing reel is generated by a rotary arm that circles the bale and holds the film reel at its outermost end.
The silage quality depends on the bale quality of the film wrap on the other hand.
Type, age and wilting degree of the harvested agricultural produce as well as swath preparation and pre-treatment of the harvested agricultural produce (cut or uncut) plus particularly the bale pressing density and shape largely determine the bale quality. Bales with a higher pressing density contain a lower portion of air so that within the wrapped bale better silage quality can be achieved.
The quality of the film wrap is determined by the quality of the film, i.e. the manufacturing process (drawn or blown), film thickness, film coloration (white, black, green), tear strength, adhesive force as well as gas permeability and especially also the care of the operator, i.e. exact adjustment of the pre-stretching process of the film, even film overlapping and correct number of layers as well as careful bale storage.
A high degree of silage quality can be achieved if all abovementioned conditions are met.
With combinations of round balers and devices for wrapping the bales have been introduced recently, it depends on the care of a single person on whether or not a high-quality silage is obtained.